RT9525 datasheet(13/15 Pages) RICHTEK

13 / 15 page

RT9525

DS9525-01 May 2011

www.richtek.com

ISYS

VSYS

T1, T7

SYS Regulation Voltage

T2, T6

< IVIN_OC

− CHG_MAX

SYS Regulation Voltage

T3, T5

> IVIN_OC

− CHG_MAX

< IVIN_OC

Auto Charge Voltage

Threshold

> IVIN_OC

VBAT − IBAT x RDS(ON)

IVIN

IBAT

T1, T7

CHG_MAX

T2, T6 ISYS + CHG_MAX

CHG_MAX

T3, T5

VIN_OC

− ISYS

VIN_OC

ISYS − IVIN_OC

ISYS

VSYS

T1, T7

SYS Regulation Voltage

T2, T6

< USB_OC

− CHG_MAX

SYS Regulation Voltage

T3, T5

> USB_OC

− CHG_MAX

< USB_OC

Auto Charge Voltage

Threshold

> USB_OC

VBAT − IBAT x RDS(ON)

IUSB

IBAT

T1, T7

CHG_MAX

T2, T6 ISYS + CHG_MAX

CHG_MAX

T3, T5

USB_OC

− ISYS

USB_OC

ISYS − USB_OC

0.25A

-0.25A

0.5A

0.75A

-0.5A

-0.75A

4.3V

4.0V

IBAT

ISYS

IUSB

VBAT

VUSB

VSYS

VAPPM

USB 500mA Mode

Thermal Considerations

For continuous operation, do not exceed absolute

maximum junction temperature. The maximum power

dissipation depends on the thermal resistance of the IC

package, PCB layout, rate of surrounding airflow, and

difference between junction and ambient temperature. The

maximum power dissipation can be calculated by the

following formula :

PD(MAX) = (TJ(MAX)

− TA) / θJA

where TJ(MAX) is the maximum junction temperature, TAis

the ambient temperature, and

θJAis the junction to ambient

thermal resistance.

For recommended operating condition specifications of

the RT9525, the maximum junction temperature is 125

°C

and TA is the ambient temperature. The junction to ambient

thermal resistance,

θJA, is layout dependent. For WQFN-

16L 3x3 packages, the thermal resistance,

θJA, is 68°C/

W on a standard JEDEC 51-7 four-layer thermal test board.

The maximum power dissipation at TA = 25

°C can be

calculated by the following formula :

PD(MAX) = (125

°C − 25°C) / (68°C/W) = 1.471W for

WQFN-16L 3x3 package

The maximum power dissipation depends on the operating

ambient temperature for fixed TJ(MAX) and thermal

resistance,

θJA. For the RT9525 package, the derating

curve in Figure 2 allows the designer to see the effect of

rising ambient temperature on the maximum power

dissipation.

Figure 2. Derating Curve for the RT9525 Package

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

100

125

Ambient Temperature (°C)

Four-Layer PCB

RT9525 Datasheet(PDF) 13 Page - Richtek Technology Corporation

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